1,721,003 research outputs found
Lettuce fortification through vitamin B12-producing bacteria – proof of concept study
Get PDFBACKGROUND: Vitamin B-12 (cobalamin) can be produced de novo only by certain bacteria and archaea. It plays a crucial role in the health of animals and humans, which obtain it only through diet, mainly from animal products. This study aimed to identify endophytic bacterial strains capable of synthesizing vitamin B(12 )and enriching edible plants with it as a potential solution for vitamin B(12 )deficiency in vegetarians, vegans, and people with poor diets. RESULTS: An in silico genome analysis was performed on 66 bacterial genomes, including the reference strain Pseudomonas denitrificans ATCC 13867, a known vitamin B(12 )producer. The genomes were analyzed using the Rapid Annotations using Subsystems Technology (RAST) server and the MetaCyc database to verify the presence and completeness of the vitamin B(12 )metabolic pathway. The ability of the strains to produce vitamin B(12 )was confirmed with a high-performance liquid chromatography with diode-array detection (HPLC-DAD) analysis of pure culture extracts. Eleven strains produced detectable amounts of vitamin B(12 )under tested conditions. The best performing candidates were further tested for their efficacy in producing vitamin B(12 )in lettuce grown under sterile conditions on Murashige and Skoog (MS) medium with or without CoCl2 supplementation. Methylobacterium sp. strain P1-11 produced detectable amounts of vitamin B(12 )in planta: 1.654 and 2.559 mu g per g of dry weight without and with CoCl2 supplementation, respectively. CONCLUSION: This is the first time a bacterial endophyte was used to produce vitamin B(12 )in planta, suggesting that bacterial endophytes could be utilized to enhance the nutraceutical values of plant-based foods. (c) 2025 The Author(s). Journal of the Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry
The human-associated bacterium Propionibacterium acnes as a grapevine endophyte
Get PDFAnimals and plants have established a long-lasting cohabitation with a variety of
microbes, including pathogens, commensals and beneficials. Studies investigating
such associations documented numerous cases of bacterial host switches (usually
from domestic animals to humans).
The exchange of microbial symbionts between humans and plants is much less
investigated. We reported a surprising example of horizontal interkingdom transfer of the human opportunistic pathogen (P. acnes) to grapevine (Vitis vinifera L.). P. acnes was interestingly most common inside the plant's pith tissue. Phylogenetic and
population analyses place that the establishment of the grapevine-associated P.
acnes likely during the Neolithic, when grapevine was domesticated. The endophytic
subspecies of P. acnes was named P. Zappae.
An analysis of Propionibacteria in the grapevine endosphere showed that P. Zappae
is far from being the only species present in this plant as an endophyt
Grapevine colonization by endophytic bacteria shifts secondary metabolism and suggests activation of defense pathways
No full textAims
The colonization pattern of three grapevine endophytes (families Sphingomonadaceae and Enterobacteriaceae) and their putative metabolic signature in plants were analyzed on Vitis vinifera L. cv. Pinot noir to determine the behavior of endophytic strains inside plants as well as how plants respond to such microsymbionts.
Methods
Strains Enterobacter ludwigii EnVs6, Pantoea vagans PaVv7 and Sphingomonas phyllosphaerae SpVs6, were root inoculated on micropropagated grapevine plantlets and colonization was determined by double labeling of oligonucleotide probes-fluorescence in situ hybridization (DOPE-FISH) coupled with confocal microscopy. After inoculation, the metabolic signature in plants colonized by Enterobacter ludwigii EnVs6 was further studied using UPLC//tandem mass spectrometry analysis.
Results
E. ludwigii EnVs6 and P. vagans PaVv7 colonized the plantlets and were both observed on the root surfaces and as endophytes in the cortex and inside the central cylinder up to xylem vessels, but not in the systemic plant parts. Strain SpVs6 also efficiently colonized the root surface, but not the endorhiza and was therefore not detected as an endophyte. A metabolic signature in plants inoculated with E. ludwigii EnVs6 was depicted, resulting in a significant increase in vanillic acid and a decrease in the concentration of catechin, esculin, arbutin, astringin, pallidol, ampelopsin, D-quadrangularin and isohopeaphenol. Changes in the concentration of epicatechin, procyanidin 1, taxifolin and the sum of quercetin-3-glucoside and quercetin-3-galactoside, in roots and stems were also detected, showing that the effect of colonization of plants is most prominent in the stems.
Conclusions
Colonization patterns in endophytes are divergent according to the strains used. A metabolic signature suggests the activation of pathways involved in plant defense but also modulation of the production of metabolites that are keys for colonization
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Endophytic colonization of grapevine by bacteria reveals a metabolic signature suggesting activation of pathways for symbiosis and defense
Get PDFEndophytes colonize the inner tissues of plants without causing apparent disease symptoms. In several models of plant-bacteria interactions, it has been suggested that colonization by endophytes occurs in specific parts of the plant. The plant metabolic signature induced by colonizing microbiota can be used to define how this affects the plant’s immune system, growth and health. In grapevine, metabolic responses due to root-colonizing endophytes are yet unclear.
To interpret changes in the metabolome composition in planta due to endophytes, we combined i) the study of plant tissue colonization by bacteria using fluorescence in-situ hybridization and ii) the analysis of grapevine’s secondary metabolome to dissect the interactions between plants and their endobiota. We described the colonization of grapevine root tissues by three bacterial endophytes (Sphingomonas sp. SpVs6, Enterobacter ludwigii EnVs6 and Pantoea vagans PaVv7) and showed the heterogeneity of colonization patterns by these strains as well as their strategy for root penetration. After inoculation with strain EnVs6 we detected a plausible metabolic signature in plants consisitng of significant differences in accumulated stilbenes and phenolic compounds. These were differentially concentrated in control and treated plants and inequally distributed between roots and stems. Accumulation of flavonols and phytoalexins occurred mainly in roots due to root inoculation with the three endophytic strains. Such metabolic signature may be linked to an adaptative response to bacterial inoculation, suggesting involvement of the plant’s immune defenses and point at a possible role of metabolites such as phenolic compounds as key for bacterial colonization in symbiotic contexts.
The set of phenylpropanoids affected by endophyte inoculation strikingly resemble those previously reported to result in thiamine-mediated resistance to Plasmopara viticola infection. This similarity hints at the mechanistic basis of endophyte-mediated plant immunity and may explain the previously tested efficacy of this strain as a biocontrol agent
How grapevine got pimples: the interkingdom horizontal transfer of an unusual symbiont
Get PDFHumans have established a long-lasting co-habitation with a variety of animals, plants and microbes. The human-gut microbe interaction has been recently explored, and cases have been reported of microbial host transfer from domesticated animals to humans. Much less is known regarding human-plant microbial transfers. Here we report a recently established symbiosis between the human-associated opportunistic pathogen Propionibacterium acnes and the highly domesticated grape Vitis vinifera. We detected P. acnes in many grape plants using pyrosequencing of 16S rDNA and fluorescent in-situ hybridization (FISH) which localized P. acnes in specific endosphere habitats (pith and bark). We also show that recA genes in uncultivable endophytic P. acnes of grape are pseudogenes, suggesting a recent obligate symbiosis which we tentative date as being not older than 7000 years ago, an age compatible with the domestication of grape by humans. Our results represent the first documented inter-kingdom horizontal host transfer of a human symbion
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Humic acid enhances the growth of tomato promoted by endophytic bacterial strains through the activation of hormone-, growth-, and transcription-related processes
Get PDFPlant growth-promoting bacteria (PGPB) are promising alternatives in the reduction of the use of chemical fertilizers. Likewise, humic acid (HA) can improve plant growth and/or the establishment of endophytic PGPB. Although the effects of PGPB colonization or HA treatment have been studied separately, little information is available on plant response to the combined applications of PGPB and HA. Thus, the aim of this work was to understand the physiological effects, bacterial colonization and transcriptional responses activated by endophytic bacterial strains in tomato roots and shoots in the absence (control condition) and presence of HA (HA condition). Tomato shoot length was promoted by seed inoculation with Paraburkholderia phytofirmans PsJN, Pantoea agglomerans D7G, or Enterobacter sp. 32A in the presence of HA, indicating a possible complementation of PGPB and HA effects. Tomato colonization by endophytic bacterial strains was comparable in the control and HA condition. The main transcriptional regulations occurred in tomato roots and the majority of differentially expressed genes (DEGs) was upregulated by endophytic bacterial strains in the HA condition. Half of the DEGs was modulated by two or three strains as possible common reactions to endophytic bacterial strains, involving protein metabolism, transcription, transport, signal transduction, and defense. Moreover, strain-specific tomato responses included the upregulation of signal transduction, transcription, hormone metabolism, protein metabolism, secondary metabolism, and defense processes, highlighting specific traits of the endophyte-tomato interaction. The presence of HA enhanced the upregulation of genes related to signal transduction, hormone metabolism, transcription, protein metabolism, transport, defense, and growth-related processes in terms of number of involved genes and fold change values. This study provides detailed information on HA-dependent enhancement of growth-related processes stimulated by endophytic bacterial strains in tomato plants and reports the optimized dosages, complementation properties and gene markers for the further development of efficient PGPB- and HA-based biostimulant
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